1) Technical Field
The subject invention relates to a beverage filling machine for filling a container with a liquid material, preferably a carbonated beverage.
2) Description of the Prior Art
Filling mechanisms used for filling containers, such as cans, jars, or bottles, with a beverage, such as carbonated drinks, juices, water or the like, as are well known in the art. Conventional filling mechanisms feed the containers into a star wheel conveyor which individually positions each container on a rotating turntable below a valve assembly of an individual filling machine. The container moves into sealing engagement with the valve assembly by either moving the container upwardly or by lowering the valve assembly. Modern filling machines are known in the art as counter pressure filling machines as is discussed below. There may be as many as 120 individual filling machines disposed circumferentially around the turntable. The filling machines typically include a support housing having an inner fluid chamber or ring bowl disposed above the valve assembly. The ring bowl is usually annular and contains the liquid or beverage for filling the containers and has a space above the liquid for a pressurized inert gas such as carbon dioxide or nitrogen. This space above the liquid is known as the headspace. A common storage tank or reservoir feeds the ring bowl with the required liquid and gas.
In the typical filling operation, the container, which is sealed against the valve assembly, is initially purged with the inert gas from the ring bowl for a predetermined time in order to flush air and other impurities from the container. A vent tube is introduced into the container to accomplish this an other operations. The liquid is filled into the container from the ring bowl while the gas from the container vents through the vent tube into the headspace. The liquid will at least partially rise into the vent tube during the filling of the container. The gas pressure in the container and the ring bowl are equalized when filling begins. This is what is known as counter pressure which allows the liquid to flow into the container solely under the influence of gravity. After the container is filled to a desired level, the vent tube rises out of the container. Finally, gas is released from the top of the container to the atmosphere by an process commonly known as "snifting".
The beverage filling industry continuously strives for machinery and methods which facilitate rapid, economical, efficient, and sterile filling of containers. As discussed above, methods and apparatuses for filling containers with carbonated liquids have evolved into counter pressure filling machines. These counter pressure filling machines typically operate under relatively high pressures. Many of the components of the filling machine are susceptible to excessive wear and damage from the pressures created within the inner fluid chamber. One such component is the vent tube which, as discussed above, moves in and out of the container during the filling operation. As appreciated, the vent tube is sealed from certain parts of the filling machine to effectuate its operation. These tube seals can experience significant pressure differentials which can significantly reduce the operating life of the seals. Accordingly, it is desirable to maintain substantially equal operating pressures on both sides of the tube seals during the movement of the vent tube.